806
ACUS11 KWNS 190154
SWOMCD
SPC MCD 190154
SDZ000-190330-

Mesoscale Discussion 2032
NWS Storm Prediction Center Norman OK
0854 PM CDT Tue Aug 18 2026

Areas affected...Parts of western/southwest SD

Concerning...Severe potential...Watch unlikely

Valid 190154Z - 190330Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated severe hail/wind threat may continue this
evening. Watch issuance is unlikely.

DISCUSSION...A cell which formed earlier over the Black Hills in
western SD has recently intensified into a supercell while
approaching Rapid City. The 00Z UNR sounding showed relatively
modest instability (MUCAPE less than 1000 J/kg) and mid-level lapse
rates, but strong deep-layer shear around 50 kt. This ongoing
supercell should continue to pose a threat for severe hail in the
short term per recent MRMS MESH estimates. But, it remains unclear
whether it will be able to persist downstream of the higher terrain
of the Black Hills given increasing MLCIN with nocturnal cooling
occurring across southwest SD. Some short term guidance suggests a
small cluster may evolve over the next couple of hours, with some
increase in severe/damaging outflow winds possible if this occurs.
Regardless, the presence of weak instability and overall isolated
nature of the severe threat suggest that watch issuance is unlikely.

..Gleason.. 08/19/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...UNR...

LAT...LON   44100353 44470321 44110146 43350148 43080203 43180275
            43810362 44100353

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN